# Questions tagged [luminosity]

Luminosity is the energy radiated from a body per second.

113 questions
Filter by
Sorted by
Tagged with
1 vote
31 views

### If a star's luminosity doubles, does its received flux double?

If the luminosity of a star increases or decreases in some way, would the received flux increase or decrease by the same amount (linearly) or would it change by the square of the luminosity (inverse ...
• 187
1 vote
21 views

### Is there a way to calculate the habitable zone distances of a star?

What would you need to calculate the habitable zone distances of a star? I am aware of the Stefan-Boltzmann Law and Wein's Law to calculate the Luminosity of the star, and that the flux decreases with ...
• 187
1 vote
57 views

### Luminosity and absolute magnitude relationship

Context : an exercise gives the temperature, mass, distance and apparent magnitude of Sirius B and asks to calculate its density. One key step of the calculation is to get the luminosity from the ...
1 vote
81 views

### Luminosity of stars

Good afternoon, I am attempting to calculate the ratio of temperature and luminosity between two stars, one entirely made of iron and the other of hydrogen, with the same volume. To do so, I have ...
• 161
53 views

### How do we realistically calculate the monochromatic flux of an object in space?

If the collecting area of a telescope is ∆A, and it collects light for a time interval of ∆t, do we just build a telescope with a very small ∆A and make ∆t and ∆λ very small as well? Also, how do we ...
• 23
65 views

### Given a star's luminosity and a distance from said star, how can I get lux?

Today I wish to know how bright interstellar space is by calculation. I have a dataset of 1000 stars which includes their luminosities. But how do I get illuminance (lux) from luminosity (watts) from ...
14 views

### Luminosity distance relation for z around 2? SH0ES Hubble constant

Is there a luminosity distance formula valid for redshift z in range 1-3? Shouldn't this include a term for the current time derivative of the deceleration parameter (q dot)? The only luminosity ...
• 61
45 views

### Clocks at different redshift: does calculating luminosity distance shift the frame of reference?

Luminosity is energy per time. When we calculate a luminosity distance, using angular diameter distance times $(1+z)^2$, I think we are correcting the energy (from redshifted photons) by $(1+z)$ and ...
• 821
1 vote
95 views

### How can there be supermassive stars of 10000+ solar masses?

Wouldn't such supermassive stars blow themselves apart first via radiation pressure (per the Eddington limit)? But they apparently exist, or at least are plausible: Assistant Research Fellow, Ke-Jung ...
• 21.4k
68 views

• 111
30 views

### Looking for ideal calibration standards for UV / visible fluorescence

I am attempting to measure the fluorescence timing distribution (how much light is emitted over time from initial excitation) of a substance and I would like to use a solid calibrated sample (some ...
44 views

### Convert cps units to candelas / sq. meter

Spectra photometer was reported to measure luminance at given cps rate (counts per second). Is it enough data to know which luminance value it measured, given model and vendor are known?
• 101
52 views

### What could be the meaning of "illuminance" in this home device?

I bought a Xiaomi sensor that measures light intensity. The data I get from it is called illuminance_lux and the unit is supposed to be ...
• 516
1 vote
100 views

### Equations for developing a hypothetical Solar System

I am currently going down the rabbit hole of writing a story but I would like it to be set in a universe which is believable. Therefore I am trying to create a hypothetical solar system in which the ...
153 views

### How do we experimentally estimate the luminosity of a distant star?

While calculating the matter density of the universe, we need to find luminosity. How do we experimentally estimate the luminosity of a star?
188 views

### Why the factor $(1+z)^4$?

I am reading through Gravitation by Misner, Thorne and Wheeler. In the exercice 29.5 (page 794) it is asked to calculate the flux of energy $S$ for a distant source in a flat spacetime. The end ...
• 1,335
20 views

### Does the $M/L$ ratio have an implied band?

When I look at the NED database, I see the Luminosity quoted for six different bands (X-Ray, UV, Visible, Near IR, Far IR, Radio). My issue is trying to interpret the $M/L$ ratios I've seen ...
• 584
1 vote
438 views

### What is the luminosity of the Milky Way?

This question may appear to be the same as What is the luminosity of the Milky Way galaxy?, but that question references a value of $5\times 10^{36}\space W$, which comes from a Wiki page which ...
• 584
263 views